Refrigerating apparatus



Dec. 14,1937..

D. E. MACCABEE REFRIGERATING APPARATUS Original Filed Sept. l, 1923 SMS/QM, f @Q n.

anion/uz 14 atented Dee.. t4, i937 nurnrcnna'rrno Arrana'rns David E. Maccabee, Dayton, Ohio, assigner, by

mesme assignments, to General Motors Corporation, a corporation of Delaware application September ll, 1928, Serial No. 303,598

Renewed March 22, 1933 maints.

This invention relates to refrigerating apparatus and particularly to arrangements for controlling the circulation of refrigerant in such apparatus. 1

One of the objects of the invention is to provide an improved control system particularly adapted to multiple installations which automatically prevents the circulation of refrigerant in such unit or units of the system as do not need refrigeration.

Another object of the invention is to provide an improved refrigerating system in which one condensing element supplies a number of evaporating elements with refrigerant and automatically maintains each of them at a predetermined temperature limit independent of the remaining elements.

Further objects and advantages of the present invention will be apparent from the following description, reference being had tothe accompanying drawing, wherein a preferred form of the present invention is clearly shown.

`In the drawing:

Fig. 1 is a diagrammatic representation of one form of refrigerating system arranged in accordance with my invention; and

Fig. 2 is a vertical section of a control valve.

It has been previously proposed to provide a numbervof evaporators which are supplied with refrigerant from a common condensing element and to operate the system so as to maintain the different evaporators at diierent temperatures. None of the systems of this character of which I am aware have provedocompletely successful because the diierent evaporators are not entirely independent of each other and because the condensing element does not circulate refrigerant through the various evaporators in accordance with the refrigerating demand upon each. The diiiculties experienced have been the more pronounced in cases in which it is sought to maintain' widely different temperatures. My invention is concerned with providing a simple, economical and reliable system which' will satisfactorily maintain widely different temperatures and in which the various refrigerating elements are operated absolutely independently of one another.

Referring to the drawing t0 designates in general a condensing element for withdrawing gaseous refrigerant from a vapor conduit il, liquefying the refrigerant and delivering it to a liquid supply conduit l2. The condensing element may be of any desired type, for example it may include the usual motor M, compressor 'l5 and condenser lt, the motor being actuated in 4response to the connected in vparallel between the liquid supply conduit and the vapor exhaust conduit Il for cooling compartments 20a and 2l a. The evaporators are connected to the conduit H by means of independent outlet conduits 23 and 2t. Preferably each of the evaporators is of the ooded type and includes a reservoir for liquid refrigerant which is kept at a constant level therein by means of a float valve, not shown herein but fully disclosed in the patent to Osborn 1,556,708, October 13,-1925.

In the outlet of each evaporator, at any suitable point between the evaporator proper and the conduit Il, is placed a shut-off valve 26 or 28, each represented diagrammatically as having a Valve casing 30, a valve stem 3i; and a exible metal bellows 32 sealed to the casing and to the valve stem to act as a packing. Each of the valves is positively actuated either to closed or to fully open position in response to the pressure existing within its corresponding evaporator by any suitable mechanism herein illustrated as lncluding the following. The valve stem is mounted at the free end of a third class lever 30 pivoted at 35 and urged-down to close the valve by means of an adjustable spring 36. Between the pivot and the valve stem the lever carries an armature 3l near which is placed the core of an electromagnet 38 which may be energized by current from the mains [9 through the leads 39 and t0. Each lead 39 includes a switch il or 02 for making and breaking the circuit through the electromagnet. 'I'his switch may be constructed as shown in the application of Jesse` G. King, Serial No. 124,160, filed July 22, 1926, now Patent 1,805,701, issued May 19, 1931, and is diagrammatically represented as including a flexible metal bellows M, connected to the outlet conduit 23 or 24, and which closes the switch when the pressure in the conduit and consequently in the evaporator is above'a certain high value and opens the switch when the pressure is below a certain low value. The value of the pressure at which the switch -will open or close can be regulated as is well known in the art by adjusting spring means diagrammatically represented by the spring 45.

In Fig. 2 I have shown the particular form of construction which I prefer for the shut-off valves 26 and 28 which aredescribed above in connection with the diagram shown in Fig. 1. A valve casing |30 is provided with an inlet opening l3l Sti' and an outlet opening will,A the passage between these openings being controlled by a stop valve l 33 cooperating with the valve seat i3d. A closed housing |35 of non-magnetic material is hermetically sealed to the casing |30 in any suitable manner and contains a magnetic plunger |36, which carries the valve iiijand which is urged downwardly to close the valve by a spring |31 in the housing. A solenoid |38 surrounds the housing |35, being placed in a casing |39, also secured to the valve seat. Electric connections it@ are made in the casing |39 and are adapted to be connected with the leads 39 and iii for energizing the solenoid. It will be understood that when the solenoid is energized the valve will be suddenly opened and that when the solenoid is de-energized the Valve will be abruptly and positively closed.

The system above described operates as follows: Assume for example, that it is desired to maintain the temperature of evaporator 2U between the limits of 3 and 14 F. If sulphur dioxide be used as refrigerant, the switch il will be set to close (which opens the valve 26) when the pressure in conduit 23 is atmospheric (0 pounds per square inch gauge) at which pressure the temperature of the evaporator will be 14 F. The switch will be set to open when the pressure is a vacuum of 10 inches of mercury, corresponding to a temperature of -3 F. Thus whenever the evaporator reaches its maximum permissible temperature, the valve 26 will open to permit refrigeration, and this valve will remain open untiLthe evaporator 2U has reached its minimum permissible temperature at which time it will be abruptly and positively closed. If the evaporator 2| is to be maintained at temperatures between 35" and 501 F. the switch A6 would be set to close, and thus open the valve 28, at a. pressure of about 18 pounds per square inch gauge, and to open, and thus close the valve 2li, at a pressure of about 9 pounds per square inch gauge.

Whenever either switch ti or 132 is closed and consequently whenever either valve is open, the pressure of the vaporized refrigerant in the vapor conduit ii closes the switch It to operate the compressor, which will then evaporate refrigerant in such evaporator or evaporators asl are in communication with conduit il. The compressor will continue to operate as long as refrigeratlon is required in either compartment and as soon as the refrigeration demand of either compartment has been satised the switch M or 42 will open and thus close abruptly the corresponding shut-oi valve. This will completely close the outlet of the evaporator independentlyv of the condition of the rest of the system. Whenever the refrigeration demand of all of the evaporators has been satisfied, all f the shut-off valves will be closed and the compressor will immediately reduce the pressure 'in the conduit il to a -point at which the switch IB will open to stop the compressor.

It is thus apparent then that refrigerant will be circulated in any evaporator whenever there is a'demand for refrigeration and that as soon as this demand is satised the circulation of refrigerant will cease whether or not refrigerant isbeing circulated in another evaporator. .Also

due to the snap action of the shut-off valves, each aioaow valve will at all times either fully open or fully close the outlet conduit of the corresponding evaporator. When any valve is open it will remain fully open as long as there is any demand for refrigeration and refrigerant can therefore be circulated at the maximum rate as long as refrigeration is required.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. A refrigerating apparatus comprising in combination an evaporator, means for withdrawing gaseous refrigerant from the evaporator, a valvefor controlling the outlet of the evaporator, means including a magnetic device for positively opening and positively closing the valve and means responsive to the pressure within the evaporator 'for energizing the magnetic device.

2. A refrigerating apparatus including an evaporator, means for withdrawing refrigerant from the evaporator, resilient means constantly tending to close the outlet of the evaporator, electromagnetic means for overcoming said resilient means to open the outlet of the evaporator, and means for energizing said electromagnetic means.

3. A refrigerating apparatus including a closed refrigerant circuit including aA compressor, a condenser and an evaporator, an enclosed electromagnetic valve means sealed to the closed circuit for controlling the ow of refrigerant through the evaporating means, and switch means located without the closed refrigerant circuit for controlling the energization of the enclosed electromagnetic valve means.

4. A refrigerating apparatus including a closed refrigerant circuit including refrigerant liquefying means and refrigerant evaporating means, valve means for controlling the flow of refrigerant through said refrigerant circuit at the 0utlet of the evaporating means, spring means for resiliently urging said valve to closed position to shut on the discharge of refrigerant from the evaporating means, electromagnetic means acting upon said valve means to overcome said spring means to open the valve, said valve means and said spring means being located within the closed refrigerant circuit and hermetically sealed therein, an electric circuit for supplying electric energy to said liquefying means and said electromagnetic means, and switch means in said electric circuit for controlling the energization of said electromagnetic means to open said valve means.

5. A refrigerating apparatus including a closed refrigerant circuit comprising a compressor, a condenser and an evaporator, valve means `en closed within and hermetically sealed within the closed circuit for controlling the iiow of refrigerant through the evaporating means, an electromagnet for operating said valve means, and switch means located without the refrigerant circuit for controlling the energization of the electromagnet and thereby the actuation of the valve means.

DAVID E. MACCABEE. 

